There's a number of popular magazines at bigger newsagents on the subject of videography (yes, there is such a word!), and you'll find lots of adverts for various devices for converting analogue audio/video (scart or individual connectors) to or from digital (firewire or USB). Phone a few dealers, tell them what you need, and see if you can get a good price.
If you're fussy about quality it's best to steer clear of the cheap & cheerful.
If you're VERY fussy about picture quality and you have a lot of VHS tapes you could check ads in the same mags and splash out for a VHS machine with a TBC (timebase corrector which stabilises the picture syncs) or a digital noise reduction function, preferably both. They make a big difference.